1. Field of the Invention
This invention relates to a communication network and, more particularly, to an optical receiver that comprises an activity detector powered from a lower power supply (e.g., lower supply current) produced from a first portion of a network interface, and for detecting an incoming signal to the receiver and forwarding a status signal used in enabling a higher power supply (e.g., higher supply current) that powers the remaining, second portion of the network interface as well as a data processing signal path of the optical receiver.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art or conventional by virtue of their inclusion within this section.
Communication networks are generally well-known as containing at least two nodes interconnected by a communication line or link. Each node may include both a transmitter and a receiver, generally referred to as a transceiver. The transceiver provides an interface between signals sent over the communication link and an electronic subsystem which can operate upon the signal within, for example, the digital domain. If the communication link is an optical fiber, then the receiver circuit converts light energy to an electrical signal. Conversely, the transmitter can convert electrical signals to an optical signal that is then forwarded across the communication link to the receiver within another node of the network.
An optical transmitter generally involves a light emitting diode, or LED. An optical receiver can include a photodetector. There are many types of photodetectors generally known to those skilled in the art. For example, a common photodetector is a photodiode or PIN photodiode. A receiver, in whatever form, consumes considerable amounts of current and, therefore, must be powered from a power supply that is capable of sending significant current into the trans-impedance amplifier of the receiver when light impinges upon the photodetector. Likewise, the transmitter can also consume considerable current whenever light is driven onto the optical link. Not only would large current increase power consumption within the communication network, but also would increase heat dissipation. The translucent plastic optical link coupled near the LED's can darken and turn partially opaque if too much power is consumed and/or if too much heat is dissipated.
In addition to undesirable power consumption and heat dissipation, it is generally known that the transmitters and receivers send and receive, respectively, light only when data is being sent across the network. However, there are many times in which the network is inactive. In portable applications, where the network is powered from a battery, it would be desirable to power down the network so that battery life is extended whenever communication is inactive. Not only would battery life be extended, but the longevity of the LED's and photodetectors would also be extended. A communication network that can selectively power up and down depending on communication activity and can also periodically calibrate for optimal transmit and receive power is not only desirable, but can be important in the low power operational modes of modern integrated circuits. Conventional networks heretofore cannot easily achieve these advantages in a cost-effective manner.